Yellowish orange sandstone, sandy and silty carbonaceous shale, and coal. Alluvial plain. Thickness as much as 300 m (984 ft).
Light gray, bentonitic claystone that alternates with gray to brown sandstone interbedded with carbonaceous shale. Laterally equivalent to Lance Formation. Fluvial and flood plain. Thickness as much as 335 m (1,100 ft).
Gravel, sand, silt, and clay deposits of stream and river channels, and floodplains.
Variable deposits that range from pebble to boulder size and include sand, silt, and clay. Dominantly alluvial terrace, abandoned channel and floodplain, remnant alluvial fan, and local glacial outwash.
Dark gray shale with several zones of calcareous concretions, a basal zone of ferruginous concretions, and numerous thin bentonite beds. Marine. Thickness as much as 300 m (984 ft).
Dark gray shale with interbedded lignite and gray sandstone. Nonmarine. Thickness 200 m (656 ft).
Yellowish orange to gray, fine- to medium-grained, non-calcareous sandstone in upper part, and interbedded sandstone, siltstone, and black shale with calcareous concretion zone in lower part. Marginal marine. Thickness 30–45 m (98–148 ft).
Yellow sandstone interbedded with subordinate grayish brown and black shale and thin beds of coal. Alluvial plain. Thickness as much as 180 m (590 ft).
Dark gray carbonaceous shale, bentonitic claystone, sandstone, and coal. Alluvial plain. Thickness as much as 185 m (607 ft).
Grayish-brown silt, sand, clay, sandstone, and lignite; river, lake, and swamp sediment; as thick as 200 metres (600 feet).